In the past packaging or wrapping machines for cylindrical workpieces, such as rolls of bathroom tissue and paper towels, have suffered many drawbacks. For example, some packaging machines have not been able to package the bathroom tissues rolls or paper towel rolls as fast as these products are manufactured. This is especially true when only a small number of rolls are packaged together or when each roll is wrapped separately.
A marked improvement upon prior art packaging and wrapping machines for cylindrical workpieces was realized by an invention by Nordstrom and Rusch, disclosed in U.S. patent application ser. No. 08/671,971, now abandoned and hereby incorporated by reference. This wrapping machine utilizes a rotating carousel with a plurality of pockets arranged such that the wound paper roll is not rotated. The wrapping film and wound roll or workpiece are sequentially fed into each pocket as the carousel rotates and the wrapping process occurs as the carousel makes one complete revolution. A fully wrapped workpiece is ejected near the end of the revolution and another piece of wrapping film and workpiece are inserted. The workpieces are not rotated, relative to the carousel when wrapped; only the carousel is rotated.
The rotating carousel arrangement of the aforementioned Nordstrom and Rusch invention permits the wrapping of workpieces at rates that are equal to or higher than prior art wrapping machines and at a lower scrap rate. However, the prior Nordstrom invention is suited only for wrapping workpieces in paper wrappings. The various embodiments disclosed therein are not able to acceptably wrap workpieces in films made from polyethylene or other suitable materials. The present invention represents an improvement over the prior Nordstrom invention and the rest of the prior art packaging and wrapping machines in that the present invention, generally referred to herein as the film wrapping machine, is adapted and modified so as to be able to reliably and quickly wrap workpieces in thin film wrappers, such as printed polyethylene films.
The need for a film wrapping machine such as the one disclosed herein stems from the need or custom of wrapping bathroom tissues rolls or paper towel rolls in plastic films as opposed to paper wrappers. Many areas of the world, having more humid climates, require water proof plastic wrappers to keep bathroom tissue and paper towel rolls in usable condition. In other areas of the world not afflicted with high humidity, it has simply become the custom to wrap bathroom tissue and paper towel rolls in plastic film as opposed to paper wrappers. In either case, there is a need for a reliable and rapid wrapping machine that is capable of wrapping workpieces in thin films.
Recognizing this need, it is an object of our invention to provide a film wrapping machine that wraps cylindrical workpieces reliably at a high rate of speed with little or no scrap produced. It is an object of our invention to provide such a wrapping machine that utilizes clamping and underfolding devices to snugly wind and hold the wrapping film against the workpiece while it is wrapped. It is another object of our invention to apply the wrapper around the workpiece in a neat and secure fashion such that the wrapper fits snugly about the workpiece and there are no gaps between the wrapper and the workpiece. It is yet another object of our invention to provide a wrapping machine that is compact, can be easily moved, and is flexible with respect to the location of its infeed and exit conveyors.
These and other objects of our invention will become apparent in the descriptions that follow. We know of no prior art that teaches or discloses our invention.